This invention relates to a cooling/heating air conditioner, and more particularly, to the auxiliary heating apparatus of an air conditioner provided to more effectively heat a room during the heating cycle.
A cooling/heating air conditioner which, in general, comprises an expansion tube, an outdoor heat exchanger, a four-way valve, a compressor, and an indoor heat exchanger; said air conditioner performs room-cooling in summer and room-heating in winter as determined by the four-way valve.
As shown in FIG. 1, which is a system diagram of a conventional air conditioner, refrigerant is circulated in the direction of the arrow: solid line to indicate a cool room in summer and broken line to indicate a heated room in winter.
This is achieved by means of the four-way valve, that is, if the flow direction of the refrigerant is reversed by the switch-over of the four-way valve during the cooling cycle which circulates in the direction of the solid line, the cooling/heating air conditioner is operated in the heating cycle as the function of the outdoor heat exchanger is changed to that of a condenser from that of an evaporator and the function of the indoor heat exchanger is changed to that of an evaporator from that of a condenser.
The heating cycle may be better understood by referring to FIG. 1. Initially, refrigerant in a gas state compressed to high temperature and high pressure by a compressor 1 is introduced to the indoor heat exchanger 5 through a four-way valve 2 to be heat-exchanged with indoor air and it then flows into expansion tubes 4 and 41 after being changed into a liquid state.
The refrigerant in the liquid state is expanded to a low temperature and low pressure while it passes through the expansion tubes 4 and 41 and then is introduced to the outdoor heat exchanger 3 to be heat-exchanged with the outdoor air.
The refrigerant which is changed into the mixed state of gas and liquid as a result of the heat exchange in the outdoor heat exchanger 3 passes through an accumulator 6 which allows only refrigerant in a gas state to pass so that the compressor 1 receives only refrigerant in a gas state. The air conditioner provides heat to a room by sequentially repeating the above process.
However, the heating capability of the conventional cooling/heating air conditioner is decreased as the outdoor air temperature falls during the heating cycle because the refrigerant directed to the outdoor heat exchanger 3 is not able to absorb sufficient heat from the cold outdoor air, and to make matters worse, if the outdoor air temperature falls below approximately 5 deg. C., the room-heating by the air conditioner becomes greatly impaired.
As a method to solve the above problem, an auxiliary heating apparatus 17 is mounted on the refrigerant pipe 51 between the outdoor heat exchanger 3 and the compressor 1 so as to heat the refrigerant when the outdoor temperature falls below a fixed temperature setting.
The auxiliary heating apparatus 17, as shown in FIG. 2, is assembled in the following order: heating coils 171 are wound around the peripheral portion of the refrigerant pipe 51, the heating coils 171 are enclosed within a flexible tube 172, both ends of the flexible tube 172 are sealed with a sealing member 175 such as silicone, and caps 175a are fitted on both of the ends. Power cords 180, 181 are connected to the heating coils.
But, the conventional air conditioner having the auxiliary heating apparatus 17 is not able to offer a desired heating effect because the velocity of the refrigerant passing through the refrigerant pipe 51 is relatively fast so that there is not enough time to achieve a sufficient heat exchange between the refrigerant and the heating coils 171.
Further more, the auxiliary heating apparatus 17 is mechanically unstable and its assembly is somewhat complicated because the auxiliary heating apparatus 17 is constructed in such a way that the caps 175a are forced to fit on the ends of the flexible tube 172 enclosing the heating coils 171.